Objective Mixotrophy that combines phototrophic autotrophy and phagotrophic heterotrophy is widespread among unicellular eukaryotic microalgae and plays a key ecological role in energy flow within food webs and in elemental biogeochemical cycles. However, identifying and characterizing mixotrophic microalgae in natural waters remains technically challenging. Improving current approaches to accurately reveal the diversity of mixotrophic microalgae is an urgent task in this field. Methods Fluorescently labeled prey surrogates and feeding experiments were employed to trace phagotrophic microalgae within plankton communities. Target organisms were captured at the single-cell level through fluorescence-activated cell sorting (FACS), followed by multiple-displacement amplification (MDA) and 18S rRNA gene sequencing for taxonomic identification. On the basis of this FACS-MDA workflow, we established a methodological framework for studying the functional groups of microalgae. Results Applying this approach to multiple freshwater and seawater samples from China, we identified twenty phagotrophic microalgal species belonging to six classes and twelve genera, as well as heterotrophic consumers representing one class and three genera, demonstrating the robustness and broad applicability of this method. Conclusion This study applies the combined FACS-MDA technology to the identification of functional groups of microalgae in natural water bodies. The established technology has broad application prospects in microbial ecology. It enables deeper insights into the functional diversity and in situ feeding activities of environmental microalgae.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |